I have a requirement like pulling the data from RD and Showing as Dropdown of a property . after submission of form, the selected value of the dropdown should be display like read only dropdown format.. I applied 'Edit option as auto' and 'Read-only is display selected value'.
I address the problem by setting the Edit options to Editable, but Disable is Always. As a result, the screen will paint a non-clickable (greyed out) dropdown with the decode value. It looks a little odd but at least I don't need to deal with DOM or save the decode value to a different field and display that.
Just Create a when rule like IsReadOnly by checking Param.Readonly=-1 and use that when condition as Disable condition. so it will show you the control as Dropdown and you can see the selected values as well.
Note: ReadOnly parameter is a default parameter maintained by pega when ever you are loading any section on read-only mode it will be set as -1.